Boosted by the growing family of two-dimensional (2D) crystals, the
study of van der Waals heterostructures[1]} has emerged
in the last couple of years as one of the most active fields of research
in the science of 2D materials. The interest in these materials can
be explained by the practically infinite combinations of elementary
monolayers that can be artificially stacked to create structures with
desired properties. Among heterostructures, graphene on hexagonal
boron nitride (hBN) is one of the most studied. Both crystals are
chemically inert, have the same crystal structure and their lattice
constants only differ by 1.8%, making them an ideal match. Compared
to SiO2, hBN provides a flatter, cleaner and electronically
more homogeneous insulating substrate [2]}, [3]}, [4]}
and is now routinely used to manufacture high-performance devices.[2]}, [6]}, [7]}
Besides serving as an excellent substrate, hBN also provides graphene
with a periodical potential that, in the case of carefully aligned
crystals, can lead to small commensurate areas.[8]}
